Moving vane instrument



Dec. 19, 1933. I J STRATTQN 1,940,334

IOVING VANE INSTRUMENT Filed Oct. 21, 1932 Inventor Jerry L. Stratton H is Attorn e y.

Patented Dec. 19, 1933 MOVING VANE INSTRUMENT Jerry L. Stratton, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York 7 Application October 21,

6 Claims.

My invention relates to current-responsive instruments and concerns particularly instruments of the moving vane type.

It is an object of my invention to produce a simple, reliable, sturdy, easily constructed, highly sensitive measuring instrument having relatively little frictional torque. Another object is to produce an instrument in which a delicate suspension is unnecessary and there is no tedency for 10 pounding of pivots, thus making the instrument available for use on aircraft or in other applications where apparatus is subjected to severe vibrations. Other and further objects and advantages willbecome apparent as the description proceeds. v

In accordance with my invention in its preferred form, I provide a magnet preferably a U -shaped permanent magnet having pole pieces located opposite each other, one of which is are- 0 shaped and has its concave side facing the other pole piece. A moving vane is provided which is pivoted at one end adjacent the second pole piece. The vane is held between the two pole pieces by the magnetic field with its free end toward the portion of the arc-shaped pole piece in which the magneto-motive force is highest. The pivot of the moving vaneis so placed with respect to the arc-shaped pole piece that the airgap between the free end of the vane increases as the arc-shaped pole' piece toward the end which is in contact with the U magnet. A winding is provided which surrounds the arc shapcd pole piece and is so connected that the magneto-motive force of the winding tends to oppose that of the U magnet. Consequently, with a relatively weak current'flowing in the winding, the magnetomotive force is greatest at the free end of the pole piece and the vane remains at this end of 'the pole piece. However, as the current in the winding is increased, the magneto-motive force at the end of the pole piece is decreased, thereby reducing the effective length of the pole piece and causing the vane to deflect away from the free end. A scale may be provided to cooperate with the moving vane to give an indication of the magnitude of the current flowing in the winding.

The features of my invention which I believe.

to be novel and patentable will be pointed out in the claims appended hereto. A more complete understanding of my invention itself, however, may be obtained by referring to the following description in connection with the accompanying drawing illustrating one embodiment of my invention.

vane-is caused to deflect from the freeend of the 1932. Serial No. 638,947

Referring to the drawing, a magnet ll'prefei ably a permanent magnet, is provided with a straight pole piece 12 and an arc-shaped pole piece 13 preferably composed of soft iron. However, it will be understood that one or both of the pole pieces may be formed integral with the magnet 11 and that the magnet 11 may also, if desired, be an electromagnet in which the magneto-motive force is supplied by an electric winding. The pole piece 13 is provided with a winding 14 extending the length of'the pole piece 13 and may, if desired, consist of a flat ribbon,

successive turns of which partially overlap the preceding turn of turns for the purpose of obtaining a more uniform distribution of I the magneto-motive force along the winding 14. A magnetic vane 15 of any suitable relatively permeable material is pivoted at a point 16 which is in relatively close proximity to the pole piece 12. The pivot 16 may, if desired, be supported bythe pole piece 12, but owing to the fact that the vane 15 is magnetically suspended between the pole pieces 12 and 13, the pivot 16 serves as a guide only and need not support the moving element and need not be arranged to withstand end thrust. Furthermore, the moving element consisting only of the magnetic vane 15, is relatively lightso'that the frictional torque of the instrument is reduced to a very small value. The vane 15 cooperates with a scale 17 suitably calibrated to indicate the magnitude of 'the current or voltage of the circuit to which winding 14 is connected. Since the vane 15 cooperates directly with the scale 1'1 and no additional pointer or target is required, an instrument of this type permits utilizing very simple construction.

Since the 'airgap is shortest in the portion 18, the maximum flux tends to flow with the vane 15 in the position shown. Consequently, this is the normal position of the vane. Since the winding 14 opposes the magneto-motive force of the magnet 11, the resultant magneto-motive force in the portion 18 of the airgap will be reduced'as the current in winding 14 increases so that the position of maximum flux will be with the vane 15 deflectedaway from the end portion 18 of the airgap. As the current continues to increase, the vane 15 will deflect to the right until the magnetomotive force of the winding 14 is great enough to wholly overcome that of the magnet 11, when the resultant magneto-motive force will be greatest in the portion 19 of the airgap so that the vane 15 will assume the position 15 in order to permit the maximum flux to flow through the vane.

Owing to the fact that the two factors which control the sensitivity of the instrument, namely, the number of turns in the energizing coil 14 and the difference in length of the airgap in portions 18 and 19, may be changed without affecting the size or weight of the moving system, the sensitivity of the instrument can be made very great and can also, if desired, be varied within wide limits.

It will be understood that the permanent magnet 11 should be composed of suitably aged magnetic material, that the pole pieces, particularly piece 13, should be composed of relatively permeable material and that care is to be taken to utilize a material of relatively low hysteresis loss for the pole piece 13 which is subjected to variations in magnetization.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A current-responsive instrument comprising a permanent magnet, a pivoted magnetic vane, a pole piece adjacent said vane at its pivoted end, an arc-shaped pole piece adjacent the other end of said vane, and a Winding surrounding said arcshaped pole piece and so connected that it tends to oppose the field of said permanent magnet, said arc-shaped pole piece having one end in contact with a pole of said permanent magnet, having its concave side toward said vane and being arranged so that the airgap between said vane and said arcshaped pole piece increases as the vane deflects from the free end of the arc-shaped pole piece toward the permanent magnet in response to increasing current in said winding.

2. A current-responsive instrument comprising a magnet, a pivoted magnetic vane having its pivoted end adjacent one pole of said magnet, an arc-shaped pole piece having one end in contact with the other pole of said magnet, and a winding surrounding said arc-shaped pole piece so connected that it tends to oppose the field of said magnet, said arc-shaped pole piece being adjacent the free end of said vane with its concave side toward said vane and being arranged so that the airgap between said vane and said areshaped pole piece increases as the vane deflects away from the free end of the arc-shaped pole piece toward the magnet in response to increasing current in said winding. I

3. A current-responsive instrument comprising a magnet having an arc-shaped portion forming 7 one of its poles located opposite the portion of said magnet forming its other pole, a magnetic vane pivoted at a point adjacent said other pole portion, and a winding surrounding the arcshaped portion of said magnet so connected that it tends to oppose the field of said magnet, said arc-shaped portion being adjacent a free end of said magnetic vane, having its concave side toward said vane and being arranged so that the airgap between said vane and said arc-shaped portion increases as the vane deflects away from the free end of the arc-shaped portion toward the main portion of the magnet in response to increasing current in said winding.

4. A current-responsive instrument comprising a magnet, a magnetic vane pivoted at a point near one of the poles of said magnet, an arc-shaped pole piece in contact at one end with the end of said magnet forming its other pole, and a winding surrounding said arc-shaped pole piece so connected that it tends to oppose the field of said magnet, said arc-shaped pole piece being adjacent said vane at its free end having its concave side toward said vane and being arranged so that the airgap between said ,vane and said arc-shaped pole piece varies as the vane deflects in response to current variations in said winding. 7

5. A current-responsive instrument comprising a permanent magnet having a pair of polar projections, a magnetic vane magnetically suspended between the poles of said magnet, a scale cooperating with an end of said vane toward one of said polar projections, a current-conducting winding surrounding said polar projections and connected so as to oppose the magneto-motive force of said magnet, thereby changing the effective length of said polar projection and causing the position in which said movable member is suspended to vary in response to variations in the current flowing in said winding.

6. A current-responsive instrument comprising a stationary member including a pair of oppositely disposed polar projections, one of which is arcuate with its concave side toward the other polar projection, and means for magnetizing said 120 polar projection longitudinally and producing a magnetic field between said polar projections, a movable member composed of magnetic material suspended magnetically between said polar projections, a current-conducting winding surround- 125 ing said arcuate polar projection and connected so as to oppose said magnetizing means, thereby changing the efiective length of said arcuate polar projection and causing said movable element to deflect in response to variations in current.

JERRY L. STRA'ITON.

CERTIFICATE OF CORRECTION.

Patent No. 1,940,334. December 19, 1933.

JERRY L. STRATTON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 109, claim 5, for "projections read projection; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 23rd day of January, A. D. 1934 I F. M. Hopkins (Seal) Acting Commissioner of Patents. 

